1. Field of the Invention
The present invention relates to a sheet separating device in a packing machine that can be applied to a wraparound caser in which flat sheets positioned at the lowermost level in a magazine disposed in an inclined attitude for accommodating the flat sheets are taken out one by one as separated from each other, then the sheet is folded into a U-shape, and it is delivered to article packing and shaping devices in the subsequent step of a process.
2. Description of the Prior Art
At first, one example of a wraparound caser in the prior art will be explained with reference to FIGS. 7 and 8. The illustrated wraparound caser is composed of a magazine 02 disposed in an inclined attitude for accommodating flat sheets 01 such as corrugated cardboard paper sheets, carton paper sheets or the like; a device for separating only one sheet positioned at the lowermost level in the magazine from the other sheets, that includes seam hooks 03 which are rockable in the direction for supporting the sheets and in the direction for releasing the same, side hooks 04 operated inversely to the seam hooks for supporting the sheets, the seam and side hooks being operated in a correlated manner with each other by a cam mechanism, and a suction arm 013 having vacuum cups 014 and adapted to be rocked while sucking the sheet 01 at the lowermost level; a vacuum cup arm 06 provided with vacuum adhesion means having vacuum cups 05 and driven by a crank mechanism so as to pull down the only one sheet separated by the sheet separating device and thereafter to be held still for a predetermined period of time; fixed guides 07 and 08 adapted to be engaged with the sheet that is being pulled down for folding the sheet into a U-shape; a case pusher 09 driven by a link mechanism so as to push out the U-shaped sheet 01' nearly in the horizontal direction during the temporary stop of the vacuum arm 06; and bucket conveyor chains 010a stretched in an endless manner in association with bucket conveyor guides 011 and 012 for transporting the U-shaped sheet 011' that has been pushed out by the case pusher. In this bucket conveyor 010, during transportation of the U-shaped sheets 01', articles are fed to the U-shaped sheets 01' in the direction at right angles to the direction of traveling while constraining the flaps of the U-shaped sheets 01' with the bucket conveyor guides 011 and 012, and in the next step of the process the case is shaped by a shaping device and then delivered.
Now, description will be made on a separating device for the sheets in the packaging machine having the above-mentioned construction. A sheet 01 positioned at the lowermost level in the magazine 02 has its one end supported by seam hooks 03a and 03b, and the other end by a fixed guide 07, and further on the both left and right side surfaces, nearly at its central portion it is supported by side hooks 04a and 04b. A vacuum cup arm 06 is fixedly secured to a link 015 via a pin 016, so that they can be rocked integrally about a fulcrum at the pin 016. Reference numeral 017 designates a drive link, to this link 017 are successively articulated a link 018 and a link 019, and a four-articulation linkage is formed by these links. If a link 021 pivotably mounted at an appropriate one point 020 to the link 018 is pivotably connected to the above-mentioned link 015, then in response to rotation of the drive link 017, the vacuum cup arm 06 achieves an intermittent motion in which the arm 06 rocks between the positions 06a and 06b and temporarily stops at the position 06b.
It is to be noted that the drive link 017, the suction arm 013, the seam hooks 03a and 03b, the side hooks 04a and 04b, another drive link 09a for driving the case pusher 09 in the next stage, respective cams for driving bottom flap tackers not shown, and the chains 010a of the bucket conveyor 010 are regulated in their relative timing, and they are driven synchronously.
In the above-described construction, means for separating the sheets one by one is constructed of the suction arm 013, the seam hooks 03a and 03b and the side hooks 04a and 04b which are rocked by cam mechanisms. More particularly, at the timing when the vacuum cups 014a and 014b on the suction arm 013 suck the sheet 01 appearing at the bottom surface of the magazine, the seam hooks 03a and 03b release the sheet 01, while the side hooks 04a and 04b support the sheet 01, as shown in FIG. 7.
Subsequently, when the suction arm 013 has rocked up to a predetermined position and has separated one sheet 01, the seam hooks 03a and 03b rock to the direction for supporting the sheets and support the remaining sheets, thereafter the side hooks 04a and 04b release the lowermost sheet 01, and thereby the lowermost sheet 01 is separated from the other sheets in the magazine 02. Furthermore, the sheet separating means is constructed such that at this timing, suction of the separated sheet 01 by the vacuum cups 05 on the vacuum cup arm 06 is effected, then in coincidence with the timing for separating the one sheet 01 by downward rocking of the vacuum cup arm 06 the side hooks 04a and 04b rock in the direction for supporting the sheets and support the remaining sheets, and further, by rocking the vacuum cup arm 06 up to a predetermined position 06b, delivery of only one sheet 01 can be effected.
According to the above-described construction for separating one sheet in the prior art, at the timing when the vacuum cups 014a and 014b on the suction arm 013 suck the sheet 01 appearing at the bottom surface of the magazine, the seam hooks 03a and 03b release the sheets 01, and when the one sheet is separated by rocking the suction arm 013 downwards by a predetermined angle, the seam hooks 03a and 03b would rock to support the remaining sheets, thereafter the side hooks 04a and 04b release the sheets 01, and at that moment when pull down of a single sheet is effected by suction effects of the vacuum cups 05 on the vacuum cup arm 06, since the remaining sheets are held supported by the seam hooks 03a and 03b and the fixed guide 07 on the opposite side, when the lowermost sheet is singly sucked and pulled down by the vacuum cups 05 on the vacuum cup arm 06, there may occur the phenomenon that the lowermost sheet 01 and the sheet just above the lowermost sheet that is overlapped with the sheet 01 cannot be separated perfectly from each other due to a vacuum force generated by the fact that overlapped sheets are abruptly peeled off and hence a plurality of sheets are separated as adhering to each other. Therefore, the prior art construction involved the problem that not only the separating device can be hardly adapted to different kinds and sizes of sheets, but also reliable separation of sheets one by one cannot be achieved.